Question

The first law of thermodynamics is represented by the equation :

• A. $\Delta E=Q-W$
• B. $\Delta E=Q+W$
• C. $W=Q+\Delta E$
• D. $Q=W+\Delta E$

Answer 1

Answer: (B)

According to first law of thermodynamics "Energy can neither be created nor be destroyed, it can only be converted from one form to another"
Mathematically
$\Delta E$ or $\Delta U=q+W$
$\Delta U=$ change in internal energy
$q=$ heat absorbed
$W=$ work done
Heat absorbed by the system $\to q=+$ ve
Heat given out by the system $\to q=-$ ve
Work done on the system $\to W=+$ ve
Word done by the system $W=-$ ve